Sweet, Sour, Salty ... and Fizzy?

Sour-Sensitive Taste Cells Respond to Carbon Dioxide

Oct. 15, 2009 -- Carbonated drinks may do more than tickle and fizz; they also trigger taste receptor cells, a new study shows.

The study, published in Science, shows that the same taste receptor cells that pick up sour tastes are also activated by carbon dioxide.

That finding comes from lab tests done on mice that were genetically engineered to sideline their sour taste receptor cells.

Those mice responded to every type of taste except sour; they also didn't respond to carbon dioxide.

That sensitivity to carbonation may have evolved as a warning sign of fermenting food, or maybe it's part of the pH balance within taste buds, write the researchers, who included Jayaram Chandrashekar, PhD, of the University of California, San Diego.

"The 'fizz' and 'tingle of heavily carbonated water is often likened to mild acidic stimulation of the tongue, and in some cultures seltzer is even named for its salient sour taste (e.g., saurer Sprudel or Sauerwasser)," Chandrashekar and colleagues write.

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